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Question about sawing

Started by GeneWengert-WoodDoc, December 14, 2012, 11:13:50 PM

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GeneWengert-WoodDoc

As many of you know, I write an article in Sawmill&WoodLot magazine about sawing and drying in every issue.  Are there any topics that you would like to see or the need more explanation (3 pages) than we can give here that I could consider for a future article?  Thanks in advance for your input.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Okrafarmer

I need to get subscribed to it and read all the back issues. It's a great magazine, from what I've seen.  :)

Have you ever written about kiln-drying thick hardwood slabs?
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

Dan_Shade

equalizing and stress relieving a kiln load confuses me.

I feel like I fly by my butt when I get to that part of the drying cycle.  I'd love to see a good article on methods and theory of equalizing and stress relieving.
Woodmizer LT40HDG25 / Stihl 066 alaskan
lots of dull bands and chains

There's a fine line between turning firewood into beautiful things and beautiful things into firewood.

drobertson

Gene, thanks for asking, how about the science and myths' if there are any myth's to the blueing of SYP. When does it occurr? Why? is it actually a pre-rot condition?   thanks!
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

Tree Feller

I've been thinking about subscribing to Sawmill & Woodlot. If I had known you had a sawing and drying article in every publication, I would have already done so.

The issue that I run across the most, both on woodworking forums and in personal conversations with other woodworkers is "how dry does the wood need to be for indoor furniture?"

I've always maintained that 7% - 8% is optimum for most of the US, excluding the Mountain West and coastal regions. However, I always hear stuff like "I routinely build with wood at a 12% MC or higher and I've never had a problem." I try not to even get into that particular debate anymore.
Cody

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Stihl MS-290 Chainsaw
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GeneWengert-WoodDoc

I have an article about equalizing that will likely be in early 2013.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Okrafarmer

I always like articles that have to do with drying specific tricky species. Maybe you could do an article, or series of them, about drying tricky species, such as sweetgum, persimmon, cherry, pecan, holly, and hackberry. And I am sure there are others I'm not thinking of.
:)
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

hamish

Gene,

How about a sawing and no need to dry article, using practicle examples.

I suscribe to Independant Sawmill and Woodlot Magazine,  its has been alot of reading back to 1997.

Jeremy
Norwood ML26, Jonsered 2152, Husqvarna 353, 346,555,372,576

learner

This has probably allready been done, but have any articles been written about the different techniques used to stop insects from destroying freshly sawn wood?
Perhaps a few environmentally safe mixtures used to do this?  Their contents and formulas?  As a New and un-educated Sawyer, I know such an article would interest me.
WoodMizer LT40 Super Hydraulic, MF-300 FEL, Nissan Enduro 60 forklift, 2 Monkey Wards Power Kraft Radial arm saws, Rockwell series 22-200 planer, Prentiss 210 loader

Leigh Family Farm

I just signed up for a subscription last month based upon the recommendations on here. As for articles, I would like to read about small drying techniques for the small guys, mainly those that are drying 300-500 bdft. (one or two logs worth) in a backyard. Maybe a small DH kiln building project that doesn't require buying expensive equipment. Thanks!
There are no problems; only solutions we haven't found yet.

slider

I have been getting Sawmillandwoodlot for several years now.It's a great magazine and do enjoy your articles in each publication.Since i deal with a good bit of beetle killed and lightning struck pine.I would like to know some better ways to delay the decaying process .And also the best way to deal with mold after sawing.I just air dry so i guess a kiln would solve the mold issue.
al glenn

vfauto

How about details on building and using a solar kiln.
The definition of insanity is to do the same things over and over and expect a different result!

GeneWengert-WoodDoc

Thanks for the input so far.  Past articles that address (directly or tangentially) some of the issues include

Solar designs in Feb 2008
Insects in May/June 2003
Equalizing and conditioning in Jul 2010
Blue stain in May/June 2009 and also in 2013
Final MC for furniture July 2011
Small DH  July 2007

Let me know if I can help on any specific issues using direct e-mail.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Jeff

QuoteLet me know if I can help on any specific issues using direct e-mail.

One thing we have always encouraged on the Forestry Forum is to keep conversations on the forum. If a question is asked or a problem is presented here, and the answer is only given privately, it makes the whole idea of having a place to help everyone that needs it diluted. The Forestry Forum has almost every single conversation that has taken place for over a dozen years, here, and available for guests and members to have at their fingertips. Only a minute number are gone, and only because the content or conduct did not belong here to begin with.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

GeneWengert-WoodDoc

Good response and you are indeed correct.  So, post a problem here and do not go with direct e-mail.

Gene
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Piston

I know this has been covered before, but I'm interested to hear what your thoughts are on air drying lumber for furniture?  Many people have said do not use air dryed lumber if your trying to build furniture.  However, in a cabinetmaking book that I'm reading right now, it points out the obvious, about how people have been building furniture long before kilns were around, and some of that older furniture is still going strong today.

As far as Sawmill and Woodlot magazine, I'm a long time subscriber and have learned a lot.  I really enjoy reading the annual sawmill and firewood shootout.  I got the "teaser" article on the firewood shootout last month, and am still waiting for the real shootout results to arrive!  Can't wait, thanks for a great magazine and some excellent articles.   ;D

If your bored, you could post a comment in my thread on using green pine as wall covering for my shop....
https://forestryforum.com/board/index.php/topic,62604.0.html  ;D
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

WDH

All of my furniture has been made from air dried lumber (and I have built a lot of it as you can see from the posts in the Woodworking Board).  Some of the lumber was brought inside and stacked to acclimate.  Some of it was not.  You have understand how wood behaves and build that in to your project.  In my climate in Georgia, the equilibrium moisture content in my house for most of the year is 9.5%.  I know this because I have taken measurements over time.  If the lumber that you are using is 12%, there  will be shrinkage, and you have to understand how that will affect what you are building, allowing for the wood to move and acclimate once in use.  Some projects are easier to do this with that with others.  Even if you have perfectly kiln dried wood that is 7% moisture, you still need to understand how that wood will behave once your project is built because I can guarantee you the the wood will not stay at a perfect 7% moisture for eternity.  It will change, and that has to be considered when you design your project.

Using 7% moisture content wood in Georgia can be a real problem when the Spring and Fall is upon us and we open up the house or use the attic fan to pull in the nice outside air.  Bad things can happen, and have.  I prefer to engineer in some shrinkage in the design, but have found swelling to be untenable.  Very untenable. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

scsmith42

Gene, thanks for asking.  Here are a few off of the top of my head.

Instability of pith wood.  Which species have very unstable pith wood (such as oak), which you want to exclude when milling, and which species have very stable pith wood which is ok to leave in the milled boards?

An explanation and comparison of :1) Slope of grain versus 2) full, half or no taper sawing versus 3) strength of the boards / beams produced.

Wood color in air dried black walnut.  Many craftspeople believe that air dried black walnut has a richer color, due to pigmentation retention.  True or false?

Wood workability versus type of kiln drying (and how does one measure "workability"?).  Some craftspeople prefer air-dried wood as they say it works better than kiln dried.  From what I've experienced, solar and DH kiln dried wood works the same as air dried, but wood dried in high temperature kilns may work different.  True or false?

Options for treating bugs in your woodpile.

A comparison of commercial and "home made" compounds for treating wood for outdoor use (that can be applied at home or on the farm/ranch).  Which products work best, etc?  Here on the Forestry Forum we have a home brew called "uncle Buck's" that would be good to include in the comparison.
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and a mix of log handling heavy equipment.

GeneWengert-WoodDoc

Regarding the issue of air drying, a kiln is a fast way to achieve the desired moisture content.  It also typically heats the wood to over 130 F so all insects and fungi  are dead.  It also evaporates the pitch or resin that would seep out from the wood when the wood was in use.  With these exceptions, the key for any wood used for furniture is to get the woodmasmclose to the in-use moisture content before you begin working it.  This is so moisture changes (which cause size changes and warp) will not occur.  Most homes and offices run about 30% RH in the winter, so that is 6.0% MC.  In the summer, they are 50% RH inside average or 9.0% MC.  Radio Shack has a digital hygrometer for $30 that can give you the RH in storage, in your shop, and in the final in-use condition.  Many studies have been done throughout the US to confirm these aVerage values.  Also, we know that a piece at 7% that is going to 50% RH will not achieve 9% MC but will be 1/2% short or more.  So a target MC is often 6.5% to 7.0% MC.  It does not matter if you use a warm room to get this final MC or a kiln or an attic.  Unfortunately, outside air drying will only get to 12% MC, as almost all of the US averages about 65% RH, summer and winter, outside.  So, after air drying, you need to bring the wood,into a shop or similar to get the lower MCs.  In the old days, they often used the rafters above the stove to store air dried, and in this location, the wood also dried further.

Now here is a real key.  Prior to central heating, a home or office was closer to 9 to 11% EMC, so kilns were not needed to get 12% MC air dried lumber to an in-use MC.  So, in the old days, kilns were not needed.

Questions?
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding walnut color and maple too...
The color is partially an oxidation reaction that Takes time.  Heat makes it go faster.  Light helps the outer 1/100".  So, rapid kiln drying generally developes lighter colors, which we like in maple and ash, but not walnut.  The colors will darken with time and light exposure.

Sometimes walnut is steamed and the heat and moisture help develop darker colors (true for almost any species).  It also helps the sapwood darken.

Special note.  Sometimes lumber is partially air dried, getting a dark color on the outside, but then is put into the kiln, where the fast, hot drying creates a light colored core.  So, the finished wood has two colors that are obvious.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding strength, slope of grain (SOG) and sawing parallel to the bark or various other tapers.
The SOG greatly affects strength, so if the grain is straight in the tree and not spiral grain or a crooked log or near a knot, the least amount of SOG and highest strength will occur by full taper sawing (parallel to the bark). For handles, drum sticks, and other critical strength products, full taper sawing is a key.  Maybe it should be for table legs, chair legs, etc.

For beams, the strength of a beam used for design is roughly 1/6 of the strength of clear wood, so the SOG is part of this safety factor.  A few people will actually test each piece of wood and sell it based on its strength rather than have this 5/6 reduction.

So, if you full taper saw, you make a stronger product.  Of course, you need to tell the customer or else your higher quality will not be rewarded with a higher price.

Ok?
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding Chemicals for logs...
I cannot legally or ethically suggest a chemical that is not licensed or approved for use on wood.  The idea is that approved chemicals will have less environmental and human risk, especially long term.  They will not be stronger than needed.  Further, when the wood is used in an enclosed environment or when it is sanded or even scraps are burned, there will be no risk to humans or to the environment.  In fact, if the chemical is still on the wood in a fairly strong amount, the law requires you to notify the buyer and you need a license to sell treated wood.  What if the wood is used for a child's toy or for a table or,counter used to prepare food, etc.

The bottom line is that a responsible person will use approved chemicals on wood.  Unfortunately, these chemicals,cannot be made easily at home.  The old homemade chemicals we see in old literature are not safe.

Questions?
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding drying of tricky species, you will find a lot of info in DRYING HARDWOOD LUMBER.  It is out of print, but you can get it on line.  Special note...if you take the on line address for a PDF file to a copy place, then can copy it direct (clear pictures) and even bind it for maybe $25.  We also talk about such things at various dry kiln association meetings.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

The best article on a very functional solar heated kiln is
http://pubs.ext.vt.edu/420/420-030/420-030.html

It is the so-called "Virginia Tech" kiln that I developed in 1978.  The article in the link is by Brian Bond who made some small improvements in the design.  It is inexpensive yet works very well.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding the pith, which is the exact center and about the same diameter as a pencil, it is not even wood.  The next 15 rings around the pith are special wood so that the tree can easily bend in the wind, ice and snow, etc.  there are microscopic differences, which lead to lengthwise shrinkage of 3% or so while more mature wood has zero shrinkage, is much weaker than mature wood, is more likely to have compression and tension wood, is often full of knots, has steep SOG, etc.  in many products, we avoid this juvenile wood.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Okrafarmer

Quote from: GeneWengert-WoodDoc on December 19, 2012, 02:16:01 AM
Regarding the pith, which is the exact center and about the same diameter as a pencil, it is not even wood.  The next 15 rings around the pith are special wood so that the tree can easily bend in the wind, ice and snow, etc.  there are microscopic differences, which lead to lengthwise shrinkage of 3% or so while more mature wood has zero shrinkage, is much weaker than mature wood, is more likely to have compression and tension wood, is often full of knots, has steep SOG, etc.  in many products, we avoid this juvenile wood.

I think some of us on the Forum (and elsewhere) have gotten into the (bad?) habit of using the terms pith, heart, heartwood, and juvenile wood a little bit too interchangeably at times. We box the heart, but heartwood is a different thing. In some species, the heartwood is most of the wood, such as in black locust. On others, it is nonexistent or very small, such as in persimmon. In many species it seems we are trying to get under the sapwood to get the "good" heartwood, and yet we are trying to avoid the juvenile wood, which, like the sapwood, is poor wood. So in a log like cherry, for instance, we are trying to avoid both, which means it's hard to get a decent piece of lumber out of a 12" diameter log. Or even a 14" log. If we have to avoid the sapwood (often 20% or more of a cherry's diameter) and the juvenile wood (often 20-30% of a cherry's diameter), what do we have left, but narrow flooring boards? So I think what SCSmith is getting at in regards to the pith wood is-- in what species can you leave some of that inner juvenile wood in your lumber without harming anything? For example, walnut comes to mind as being a much more stable wood than, oh, persimmon, for instance. When milling a log, we are trying to include as much of the lumber volume as possible for sale. If we have to throw out large portions, such as the juvenile portion, it is harder to be profitable. So how do we incorporate the juvenile wood into our lumber sales program, when is it permissible to leave some of the juv wood in a board or slab, and what species are more forgiving about this than the others? Also, about the juvenile wood-- is it always exactly fifteen rings, is that more of an approximation, and are the outer rings within the juv wood stronger than the inner ones-- ie, is it a gradual strengthening the farther out you get, or is it more of a sharp demarcation?
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

Ianab

I'm pretty sure the 15 growth rings is a generalisation, probably about right for the common Nth American hardwood species? A 15 year old oak or cherry isn't going to yield any high quality lumber, no matter how you saw it.

But a 15 year old Radiata pine or Lyptus can be a decent saw log.  Sure that area immediately around the pith  is going to be unstable juvenile wood, and react as Dr Gene states. But with growth rings ~1" wide, you get out of that unstable wood pretty quick. Those fast growing trees also never actually get to form any sap wood, effectively it's all sapwood, so you don't have the sapwood issues.

Different (more stable) species will also let you sneak in closer to the pith before the wood becomes too unstable.  Working with local Monterey cypress and Port Orford cedar, if a board is completely free of that centre pith, it's generally OK. Leaving the pith in a board is generally going to cause issues.

But the comments about taper sawing (following the grain) where possible are certainly true. Leave the taper waste in that low grade centre pith area, and taking the straight grain clear boards from the outside of the log makes a lot of sense.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Piston

The article in Sawmilll and Woodlot about taper sawing has been my favorite article since I read it.  I've reread it numerous times and it is very well written. 
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

GeneWengert-WoodDoc

Indeed, it is a gradual transition.  Certainly, 15 years is a generalization, but it a good rule of thumb.

I would suggest, and maybe we should start a new thread, that the way we become more profitable is by improved marketing and through valued added manufacturing.  The commodity called lumber needs more customization.  I am giving a keynote talk on January 17 about this and will post my talk...I could go on forever, and I know it works and have examples in the talk.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Okrafarmer

A good many of the people who buy lumber from me are looking for customization of some type.
He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty. Psalm 91:1

Operating a 2020 Woodmizer LT35 hydraulic for Upcountry Sawmill, Dacusville, SC

Now selling Logrite tools!

Writing fiction and nonfiction! Check my website.

Stephen1

Good post, so I am dropping in for a visit.
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